The treatment of portwine stains, telangiectases and other microvascular malformations of the skin has been greatly improved by laser surgery. Between 1981-83, work by Anderson and colleagues identified an approach called "selective photothermolysis", which led to effective yet essentially non-scarring treatments. This approach has since been refined and is now a mature, well-accepted, and essentially unique treatment in dermatology. At present, the laser system best satisfying the requirements of the treatment is a long-pulse dye laser, operating at a wavelength of 585 nm, the yellow region of the visible spectrum. There are a number of problems related to the operating characteristics and use of the dye laser. In the Phase I proposal, the investigator's plan to investigate the development of a solid state laser system that would replace current lasers and eliminate some, if not all of the dye-laser problems. An improved yellow source could make vascular-lesion treatment more widely available and lower in cost.